What’s Vulnerable › Vulnerabilities

CVE-2026-8161: multiparty vulnerable to Denial of Service via Prototype Pollution leading to Uncaught Exception

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-05-12 · updated 2026-06-17
• Weakness: CWE-248

Description

multiparty@4.2.3 and lower versions are vulnerable to denial of service via uncaught exception. By sending a multipart/form-data request with a field name that collides with an inherited Object.prototype property such as __proto__, constructor, or toString, the parser invokes .push() on the inherited prototype value rather than an array, throwing a TypeError that propagates as an uncaught exception and crashes the process. Impact: any service accepting multipart uploads via multiparty is affected. Workarounds: none. Upgrade to multiparty@4.3.0 or higher.

Affected products

• multiparty: before 4.3.0 — fixed in 4.3.0

How to fix

Upgrade to a fixed version: multiparty 4.3.0. Check the vendor advisory for mitigations.

References

• https://cna.openjsf.org/security-advisories.html
• https://github.com/pillarjs/multiparty/security/advisories/GHSA-qxch-whhj-8956

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